This invention relates to connectors of a type suitable for connecting together elongate members to form a framework structure which may be used, for example, as a display structure or a framework structure.
U.S. Pat. No. 4,484,429 discloses a framework connector having a first group of at least four projections extending outwardly from a main body and equi-angularly spaced about an axis normal to a plane parallel to the direction in which each projection of the first group extends from the main body, and a second group of at least four projections extending outwardly from the main body and being equi-angularly spaced about the axis, the projections of the second group each extending at between 15.degree. and 75.degree., and preferably at 45.degree. or substantially 45.degree., to the aforesaid plane.
Preferably each projection is of non-circular cross-section and there is an equal number of projections in the first and second groups. The projections of the second group are angularly staggered by half the angle between adjacent projections of the first group about the axis relative to the projections of the first group.
The main body includes a cylindrical or substantially cylindrical surface portion from which the first group of projections extend and a partial spherical or substantially spherical end portion adjoining the cylindrical portion and from which the second group of projections extend. In the illustrated embodiment, each projection is of triangular or substantially triangular cross-section having a flat or a substantially flat portion provided at the junction between each pair of adjacent sides of each triangular or substantially triangular projection.
In use, elongate tubular members are coupled between connectors to form a framework structure. The tubular members are sized to fit snugly about the projections on the connectors by slipping the open ends of the tubular members onto respective ones of the projections. While U.S. Pat. No. 4,484,429 suggested that the tubular members could be heat welded or adhesively bonded to the projections, it has become generally accepted practice to drill a hole into each of the projections and to form mating holes in each end of the tubular members so that when the tubular members are inserted over the projections, a pin can be inserted through the aligned holes to releaseably couple the elongate member to the connector. While it is desirable to have a releasable connection, the additional manufacturing step of drilling holes in each projection and the additional assembly steps of inserting pins in each connection present a disadvantage to use and cost of the connectors.